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United States Patent 5,391,329
Dougherty, et. al.Feb. 21, 1995

Process for making a solid optical limiter containing a graded distribution of reverse saturable material

Inventors: Dougherty; Thomas K. (Playa Del Rey, CA); Elias; William E. (El Segundo, CA); Kost; Alan R. (Woodland Hills, CA); Klein; Marvin B. (Pacific Palisades, CA).
Assignee: Hughes Aircraft Company (Los Angeles, CA).
Appl. No.: 109,884
Filed: Aug. 23, 1993

Intl. Cl.:B29D 11/00;
U.S. Cl.:264/1.7; 156/228.;
Field of Search:1.7;2.7;320;325;1.9;1.1;216

References Cited

U.S. Patent Documents
3,582,424Jun., 1971Norvaisa 156/245
4,360,483Nov., 1982Ayres 264/ 2 .7
4,659,407Apr., 1987Lacotte et al. 156/228
4,878,973Nov., 1989Ohtake et al. 264/ 1 .7
5,080,469Jan., 1992McCahon et al. 359/241
5,172,278Dec., 1992Tutt et al. 359/885

Primary Examiner: Vargot; Mathieu D.


An improved process is provided for making optical limiters having a graded axial distribution of a reverse saturable absorber compound, such as a buckminsterfullerene, in a host matrix, such as polymethyl methacrylate or polycarbonate. The process of the invention includes: (a) dissolving the reverse saturable absorber and the host matrix in a suitable solvent to form a solution having a preselected ratio of reverse saturable absorber to host matrix; (b) casting the solution onto a surface to form a film; (c) evaporating the solvent to form a free-standing film; (d) performing steps (a)-(c) for each different desired ratio of reverse saturable absorber to host matrix; (e) stacking the free-standing films in a desired order; and (f) hot-pressing the stack to form the optical limiter having a graded distribution of the reverse saturable absorber in the host matrix. If desired, the stack of films can be placed in a die for hot-pressing. The films can be pre-cut to the shape of the die.

15 Claims, 7 Drawing Figures

Government Interest

This invention was made with United States Government support under Contract No. N62269-90-C-0239 awarded by the Department of the Navy. The United States Government has certain rights in this invention.

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